OK, I have a linux box setup where I work. THe building is entirely Windows NT/2000 based, with no linux servers anywhere. I have my linux box setup with 2 NICs in it, one connected to this corporate network (which has a T1 secured with a Sidewinder Firewall system), and the other NIC goes to a DSL router (completely open and unsecured).
I am using this DSL line to get Internet access, since the proxy server runs Microsoft proxy server, and machines need to have Microsoft Proxy Client installed to work. Well, Linux won't connect through this proxy, that is why I have the extra DSL.
What I'm asking is how can I secure the corporate network connection from the DSL so that users can't hack through the DSL line, through my linux box (which is always on) and into the corporate network, completely bypassing the sidewinder firewall they have setup.
I need to know what to setup so that I can get Internet and run some services (such as apache and mySQL) through this DSL, but not allow any connections going through the DSL line to access the other NIC.
Please help me on this, it would be greatly appreciated. Thanks in advance.